1. The Field of the Invention
The present invention generally relates to sensors. More particularly, embodiments of the invention relate to vibrating wire gauges.
2. The Relevant Technology
Vibrating wire gauges are widely used in a variety of applications, including measuring the magnitude of various properties and forces in many construction projects, including buildings, bridges, dams, piles, tunnel linings, pipelines, anchors, and others. The gauges have been adapted to monitor stress, strain, deflection, pressure, displacement, fluid level, angular motion, and temperature. Although advancing technology has produced other types of sensors, the vibrating wire gauge is often considered the best sensor for use in many settings, due to the sensor's long-term reliability.
The vibrating wire gauge generally operates on the vibrating wire principle which states that a wire vibrates at its resonant frequency when plucked. The resonant frequency is determined by
  v  =            n              2        ⁢                                  ⁢        l              ⁢                  σ        μ            where v is frequency in cycles/time, n is 1 cycle for the fundamental (non-harmonic) vibration mode, l is the length of the wire, σ is the wire tension (or stress) in force/area, and μ is the wire's length density in mass/length. The gauge may be constructed so that a wire is held in tension inside a small diameter, thin-walled tube that is welded or otherwise attached to a structural member. An electromagnetic coil may be used to pluck or excite the wire and measure the frequency of vibration. The frequency is then used to calculate any number of the structural member's physical properties, typically by applying a series of calibration factors.
In conventional systems, the wire is excited using a wide spectrum of frequencies and the wire's resonant frequency is measured. Before a second measurement may be taken, the wire is excited a second time after the wire is allowed or forced to stop vibrating. This time delay may be undesirable when multiple measurements of the vibrating wire need to be taken in succession.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.